ABSTRACTS Conference on Innovating Microbial Pesticide Testing 13-16 September 2022
Abstracts OECD Conference on Innovating Microbial Pesticide Testing 13-16 September 2022 Paris, France
DAY 1 Session 1: Regulatory Requirements for Human Health Testing and Current Test Guidelines for Mammalian Testing and Opportunities for Developing Alternative Methods EFSA’s role in the peer review of the risk assessment of plant protection products based on microorganisms: Considerations for improving study designs Christopher Lythgo, European Food Safety Authority, EU The roles of the different actors in the submission and evaluation of dossiers to support regulatory decision making in the EU including the role of EFSA is outlined. The key legislation regarding data requirements, organism strain approval criteria and product authorisation decision making criteria is also outlined along with the guidance and support that is in place for those preparing dossiers and the competent authorities that have to evaluate the dossiers. The main decision making criteria that the data from studies has to deliver information on are: -Micro-organism / virus Identity, specifications and methods for ensuring specification compliance. -Absence of pathogenicity to humans of a strain / viral isolate. -For bacteria absence of known functional and transferable genes coding for resistance to relevant antimicrobial agents as defined in the data requirements. -Absence of infectivity or causation of unacceptable health effects in humans or animals -There being sufficient treatment options for humans and animals to be effective against the micro-organism. -Identifying metabolites of concern. -Harmful effects on human or animal health arising from exposure to the micro-organism and metabolites of concern remaining in or on plants or plant products. -Residues occurring have adverse effects on animal health. -Assessing groundwater exposure by metabolites of concern. -Absence of pathogenicity to terrestrial vertebrates. -Margin of exposure below toxic effects on terrestrial vertebrates originating from plant protection product use. -Lack of pathogenicity to aquatic organisms, bees, arthropods other than bees or if pathogenic a risk assessment that under field conditions impact on these organism group populations would not occur. -Margin of exposure below toxic effects on aquatic organisms, bees, arthropods other than bees originating from plant protection product use. -When micro-organism was not isolated from soil, lack of pathogenicity to meso-and macro-soil organisms or if pathogenic a risk assessment that under field conditions impact on these organism group populations would not occur. -Margin of exposure below toxic effects on meso-and macro-soil organisms originating from plant protection product use -When there might be effects on populations of non target terrestrial plants if the micro-organism has a herbicidal mode of action or is closely related to a known plant pathogen Key criteria for study design / improved study design need to include: -The issue of sensitisation potential (skin and respiratory) for humans, is anything possible. -Exposure / micro-organism dosing method to address pathogenicity and / or infectivity / clearance need to consider information on biology of the micro-organism. -Study design durations to address pathogenicity and / or infectivity / clearance need to consider information on biology of the micro-organism. -Which non target test organism species / whether different test organism species might be better for investigations, considering ability to maintain them (both before testing and in the context of giving reliable control results). -Which non target test organism species / whether different test organism species might be better for investigations, considering their relationship to the active microorganism strain being commercialised and its biology.
Regulatory Requirements for Human Health Testing with Microbial Pesticides in Australia Maria Trainer, Australian Pesticides and Veterinary Medicines Authority (APVMA), Australia The Australian Pesticides and Veterinary Medicines Authority (APVMA) is the statutory authority responsible for the regulation of agvet chemicals up to the point of sale. There are legislated requirements that the APVMA must be satisfied that all actives and products are safe for humans, including through the consumption of residues in food and for the environment, are effective when used in accordance with label directions, and do not unduly prejudice trade between Australia and places outside Australia. Labels for chemical products must contain adequate instructions to use the products safely. The APVMA takes a risk-based approach to regulation, and has limited prescriptive requirements for how these criteria can be met. We seek to ensure data packages and arguments are adequate to address the statutory criteria, taking into consideration both the underlying toxicity, and the likely exposure resulting from use in accordance with the label instructions. The risk assessment also considers effects on sensitive sub-populations. The flexibility of data requirements in Australia allows an opportunity for the incorporation of new assessment methodologies as they become available. To assist in this process, a pre-application assessment process is available providing an opportunity for potential applicants to discuss proposed data packages prior to submitting, or even preparing, an application. We will take into consideration a range of factors in determining the required assessments for both conventional and novel pesticides, to ensure satisfaction in relation to the statutory criteria as well as an appropriate regulatory response.
Human Health Risk Assessments for Biopesticides in the US - Industry Perspective on Development of Alternative Methods Leah Zorrilla, Bayer CropScience, United States The regulatory requirements to register microbial pesticides in the United States were first established in 1983 and revised in 1996 (OPPTS Series 885). To specifically address human safety for these unique and diverse microorganisms, the required regulatory studies are designed to not just evaluate toxicity, but potential pathogenicity and infectivity of the microbe. These guideline studies, through various routes of administration, evaluate whether or not the microbe has the potential to cause infection or disease. In addition, standard acute “6pack” studies, normally run with conventional pesticide active ingredients and their formulated products, are also required on the microbial formulation, which helps aid in categorizing hazard potential for the label and for safe use of the microbial pesticide product. Since the initial inception of these test methods, there have been efforts to reduce, replace, and refine the use of animal testing across industries. To that end, the US Environmental Protection Agency published a memo in 2019 outlining its goal to eliminate the request of and funding for mammalian studies by 2035. This goal is supported by the recent exponential increase in new approach methodologies (NAMs), which have the potential to better predict human health hazard for risk assessment purposes. As NAMs testing methodologies have been refined, several study designs have been validated and these alternative acute toxicity testing (OECD and EPA) guidelines are now accepted by regulatory authorities in many regions of the world. However, the validation of the alternative methods has mainly focused on single chemical substances, with limited testing of formulated conventional pesticides or microbial pesticides. This presentation will discuss some of the challenges for testing microorganisms in NAMs.
Regulatory Requirements for Human Health Risk Assessment in the EU - Industry Perspective on the Development of Alternative Methods José Carvalho, Certis Biologicals, Germany The EU Regulation for Plant Protection Products (Reg. 1107/2009) sets a common regulatory framework for Chemicals and Biocontrol technologies, including Microorganisms. Even if a different set of data requirements exist for “microbials”, the Regulation was developed with (single) chemical substances in mind, and does not account
for the specifics of microorganisms’ biology, and the fact that a microorganism is a “mixture” of substances. Testing methodologies to address the data requirements are still based on the concept of single entities being assessed – e.g. secondary compounds produced by the microorganisms are being dealt with as “metabolites” of the active substance, as if they were a degradation product from a synthetic chemical active substance. The EU Data Requirements have been set for microorganisms and secondary metabolites without considerations of available testing methods to address them. Adaptation of the chemical testing guidelines is therefore necessary to address the data requirements but this is not always possible or suitable. The absence of appropriate methodologies has led to several microorganisms facing non-approval or non-renewal in the EU, based on data gaps (mostly because data cannot be generated due to methodology shortcomings), and being classified as potential sensitizers in the recent EU data requirements revision until testing methods are made available to prove the contrary. Deviations from the current testing methodologies (developed for Chemical substances) as well as alternative test methods should be agreed upon by OECD Members to avoid repetition of animal testing. A microorganism is a biological mixture, which includes the secondary metabolites (SM), and therefore it should be recognised that such mixture has been tested in toxicology tests (with the MPCA/MPCP) to prevent repeating animal testing with individual SMs. This talk will focus on the EU regulatory requirements (for human health) aiming at identifying the data points for which methodology should be adapted/developed, and agreed upon, to avoid the repetition of animal testing, particularly in relation to secondary metabolites assessment.
Session 2: Overview of New Approach Methodologies (NAMs) and Other Ongoing Research in Testing Methodologies A Successful Case Study for NAM Development: Skin Sensitization Nicole Kleinstreuer, NIEHS, NICEATM, United States In 2013, the OECD published an adverse outcome pathway (AOP) for skin sensitization linking molecular initiating events and cellular and tissue effects in the sensitization process to specific adverse outcomes. Several in vitro testing methods for assessment of dermal hypersensitivity mapped to key events in the AOP have been validated in international interlaboratory ring-trials, and combinations of these methods (so-called “defined approaches”) have been shown to provide superior performance to the existing animal tests when compared to human data. It is clear from these efforts that while no individual in vitro test can recapitulate the hypersensitivity response in its entirety, integrated strategies using varying combinations of in vitro, in chemico, and/or in silico methods could be highly accurate in identifying potential skin sensitizers. Tremendous efforts were put forth under the OECD project to curate high-quality reference datasets of unprecedented size, and to develop a novel defined approach (DA) guideline, the first phase of which covers DAs for hazard and potency category prediction. Other DAs for future consideration provide point of departure estimates that can be used for quantitative risk assessment. To further investigate the utility of these approaches, NICEATM solicited chemical nominations from ICCVAM federal agencies and ICATM partners. Just under 200 substances, including pesticides, formulations, excipients and industrial agents, have been tested to date and analysis of the data is ongoing. A subset of this data has already been used by the US EPA in their 2020 “Draft Human Health and Ecological Risk Assessments for Several Pesticides for Several Isothiazolinones”. Recently initiated projects under the OECD workplan include substituting “me-too” assays as information sources in existing DAs, and refining and assessing the probabilistic Skin Allergy Risk Assessment (SARA) model under a partnership with Unilever to provide points of departure for quantitative risk assessment. This talk will discuss the development and application of NAMs in regulatory decision making, and how defined approaches have been demonstrated to be more reliable and human relevant than the commonly employed in vivo test methods.
Human Health Risk Assessment in the EU and the Potential to Develop New Approach Methodologies Philip Marx-Stoelting, German Federal Institute for Risk Assessment (BfR), Germany Risk assessment methodologies need to ensure a high level of safety for human health and the environment. At the same time, they have to be reliable and efficient to warrant that all partners in the risk assessment process, applicants, authorities and consumers, can come to sound conclusions with appropriate resources and within a reasonable time. New approach methods (NAM) offer many advantages to achieve these goals. Moreover, the development of protocols to apply NAM in risk assessment can reduce animal testing, which has only a limited value for some potential hazardous properties of microbial biopesticides anyway. Since there is an urgent need for approval of low risk active substances considering the requirements of the EU Chemicals Strategy for Sustainability, application of new approach methods (NAMs) in the field of bio-pesticides seems to be very promising. However, for the various types of active substances used in bio-pesticides different endpoints need to be addressed by diverse NAMs and respective decision strategies. Microorganisms as one type of active compounds used in bio-pesticides may be associated with hazardous properties including antibiotic resistance, pathogenicity, infectivity or sensitization and the production of metabolites of concern. Here whole genome sequencing may be informative to assess these properties. In addition, an IATA to detect sensitizing properties has been developed that could be applied to address the various hazards in a NAM based strategy. In contrast, natural compounds as another type of active ingredients may be associated with similar hazards as other chemical substances. Here too, NAM could help in hazard identification considering improvements in AOPs and in AOP based next generation risk assessment (NGRA). However, ab initio testing of chemical substances by NAMs is still under development in European projects such as RiskHunt3R or PARC and not yet available for regulatory purposes. RNA as a third type of potential low risk active substances is finding its way into pesticidal applications. For analyzing potential hazards related to RNAi as a mode of action, bioinformatics may help as the sequence of the RNA used as active ingredient is usually very target specific. Hence, comparative sequence analysis per se may allow for concluding on potential hazardous properties. In summary, a combination of NAMs within a tiered testing and NGRA strategy considering specific hazards associated with different types of active substances used in bio-pesticides, can help to ensure a high level of protection of human health reliably and efficiently.
Considerations for Developing In Vitro Studies as Alternatives to Acute Toxicity Testing: Understanding Variability in Reference Data David Allen, Integrated Lab Systems, United States Historically, toxicity testing has been conducted using in vivo test methods. Confidence in data from these methods is such that regulatory hazard classification and labeling systems have been designed around their results. To establish confidence in new approach methodologies (NAMs), we must demonstrate that they are as good as or better than the existing in vivo test method. For many toxicity endpoints there is no NAM accepted as a complete replacement for animal use because hazard categorizations based on data from the NAM do not always agree with hazard categorizations based on in vivo data for the same chemical set. However, discordance with in vivo results may not always indicate that the NAM is generating an incorrect prediction. To establish confidence in NAMs, it is critical to understand any variability inherent to the in vivo test a NAM is intended to replace, as this variability will directly affect the expectations for performance of NAMs that seek to replace it. This presentation will discuss efforts to understand the reproducibility of several in vivo test methods and how variability in those results should be considered when comparing to a NAM.
New in vitro methodologies that can be applied for the study of biopesticides’ hazard by the oral route Valérie Fessard, French Agency for Food, Environmental and Occupational Health & Safety (Anses), France Bacillus thuringiensis (Bt) is a Gram+ bacterium belonging to the Bacillus cereus group. It has been used increasingly since the 20th century as biopesticide due to its insecticidal activity linked to the production of Cry and Cyt toxins. Because Bt shares some virulence genes with the B. cereus sensu lato that is on the top list of bacterial agents causing foodborne outbreaks (with especially gastro-intestinal symptoms) in Europe, the risk that Bt can also be involved in these outbreaks has been raised. Recently, a restrospective analysis on 250 cases of foodborne outbreaks pointed out the presence of Bt alone for 19 cases. The genomic analysis of these strains was not able to differentiate them from commercial Bt (Bonis et al 2021). Public authorities are therefore claiming for complementary data on Bt potential toxicity. In this study, a panel of 31 Bacillus strains (24 Bt and 7 non-Bt) was investigated. It include i) 10 Bt biopesticides (5 kurstaki, 2 aizawai, 2 israelensis and 1 tenebrionis), ii) 7 Bacillus strains isolated from foodborne outbreaks, among which 4 identified as Bt, iii) 14 collection Bacillus strains including 10 Bt and iv) 2 reference B. cereus sensus stricto strains (ATCC-14579 and -10987). BHI bacterial culture supernatants obtained from the beginning of the stationary phase were tested on human intestinal Caco2 cells (range from 25 to 0.1% dilutions in cell medium). Cytotoxicity was assessed by measuring the mitochondrial activity of Caco2 cells with the MTT assay after a 24 h treatment. The inflammation response was also measured by the release of interleukin 8 (IL8) in cell medium using ELISA. The supernatants from all the 7 Bt kurstaki and aizawai strains showed a moderate cytotoxic effect with some increase of IL8 release. The SA11Δcry mutant showed the same effects, suggesting that Cry toxins are not involved in these cell responses. Moreover, similar results were obtained with the supernatants produced by Bt strains isolated from foodborne outbreaks. In contrast, the 2 samples available for Bt israelensis did not show any cytotoxicity nor IL8 release. Among the 10 collection Bt strains, only one showed a slight increase of IL8 while 50% were not cytotoxic. Among the other non-Bt strains of the collection, none increased the release of IL8 but 3 corresponding to B. cytotoxicus and B cereus sensu stricto species induced a strong cytotoxic effect. While the reference ATCC-14579 produced a very moderate cytotoxic response, the ATCC-10987 induced a strong cytotoxicity. However, both did not show any pro-inflammatory effect. In conclusion, we showed that in vitro toxicity testing on intestinal Caco2 cells can be useful to investigate the pathogenicity of Bacillus strains including Bt. Additional tests using in vitro models of the human intestinal barrier are currently performed to check if new information can be obtained to help in a more accurate identification of the key drivers of Bacillus pathogenicity and how it can contribute to hazard assessment of biopesticides.
Advancing reliable and relevant approaches for assessing pesticide products Christopher Faßbender, PETA Science Consortium International Thousands of animals are required to assess the toxicity of a single conventional pesticide active ingredient. Due to the limited reliability and relevance of many traditional animal test methods, the legal requirements in numerous regulatory jurisdictions to reduce animal use, and the ethical implications of testing on animals, the international regulatory and scientific community is shifting towards an increased reliance on new approach methods (NAMs). PETA Science Consortium International e.V. collaborates with regulators, academics and industry to harmonize international testing requirements, and develop and implement robust, fit-for-purpose NAMs. This presentation will provide examples of our work in the area of conventional pesticide toxicity testing, including a focus on specific endpoints such as eye irritation, carcinogenicity, and avian dietary studies, as well as work conducted in collaboration with the Central Insecticides Board & Registration Committee in India to reduce animal use within the biopesticide regulations.
Building on previous efforts, this presentation will also propose a modern, flexible framework comprising five essential elements to establish scientific confidence in NAMs for regulatory use: fitness for purpose, human biological relevance, technical characterization, data integrity and transparency, and independent review. The criteria presented here is broadly applicable across human health endpoints. Updates to the criteria are based on the recognition that (1) the relevance of the NAM results need not be determined through direct alignment with the results of the traditional animal test method, and instead may be determined through alignment with, or fidelity to, human biological understanding; (2) the NAM should not be required to replace the traditional animal test method one to one, nor produce the same information generated by the traditional animal test method; (3) the currently accepted levels of reproducibility in traditional animal test methods can be used to inform performance benchmarks for NAMs; (4) ring trials may not be necessary for the assessment of the reproducibility of a NAM; and (5) preferably before a NAM is developed, its purpose should be clearly defined and discussed amongst the method developer, regulators, and the regulated industry to ensure the production of NAMs that are fit for purpose. Universal uptake of this framework would facilitate the timely development and use of NAMs by the international community.
DAY 2 Session 3: Regulatory Requirements for Non-target Organisms Non-target Organism Testing with Microbial Pesticides in the US - Regulatory Requirements and Challenges Geoff Sinclair, US Environmental Protection Agency (US EPA), United States Microbial ecotoxicity tests are used to provide information on the hazard of microbial pesticides to support the registration of pesticide products containing new active ingredients (AIs), with new uses, and for periodic review of AIs contained in currently registered pesticides (e.g., registration review). The data requirements for microbial pesticides are tiered, where Tier I tests must be performed and higher tier testing is only required if adverse effects are seen at lower tiers. Tier I data requirements include tests on birds, aquatic invertebrates, fish, nontarget plants, and terrestrial insects including bees. These tests are described in the U.S. Environmental Protection Agency’s Series 885 guidelines for microbial pesticides. Because microbial pesticides are derived from a range of naturally occurring microorganisms that include bacteria, fungi, viruses (including bacteriophage), and protozoa the guidelines to conduct these tests are not overly prescriptive but try to provide latitude to adapt tests based on the nature and hazards of each active ingredient. One of the many challenges when testing microbial pesticides is designing tests to adequately address both potential toxicity as well as pathogenicity. This talk will describe some of the nontarget organism testing approaches for microbial pesticides, including maximum hazard doses, test duration, details of tiered testing, and commonly seen problems. It will also identify some challenges posed when parameterizing and conducting tests that include exposure considerations such as the level and duration of exposure.
Canadian Regulatory Requirements for Microbial Pesticide Non-target Organism Testing Emma Babij, Pest Management Regulatory Agency (PMRA), Canada Microbial pesticides are subject to the Pest Control Products Act and Regulations in Canada. In order to be registered, a product must demonstrate acceptable risk to human health and the environment when used according to its prescribed conditions of use. Under the Act, environmental risk is defined as the possibility of harm to the environment, including its biological diversity, resulting from exposure to or the use of the product. Canada’s Pest Management Regulatory Agency takes a four-tiered approach to environmental testing of microbial pesticides, with higher tiered studies required if significant adverse effects are identified at lower tiers. The basis for the risk assessment is environmental toxicology testing on a broad selection of non-target organisms such as birds, mammals, fish, arthropods, non-arthropod invertebrates, microorganisms, and plants. Infectivity, pathogenicity, and toxicity are evaluated as adverse effects. Environmental fate data and additional testing such as acute toxicity, definitive toxicity, and chronic toxicity testing may be required as part of higher tiers. The submission of surrogate or published data, or robust waiver rationales based on sound scientific principles, may be considered to satisfy the regulatory requirements.
Where are we and where do we need to go? A Dutch perspective on the assessment of microbial pesticides Emily McVey, Board for the Authorization of Plant Protection Products and Biocides (Ctgb), The Netherlands This presentation will focus specifically on the strategies for risk assessment and approval of products based on microorganisms, including viruses, of the Dutch Board for the Authorization of Pesticides and Biocides (Ctgb). In this context, the current data requirements, the evaluation of GLP, peer-reviewed, public, and grey literature and weight-of-evidence considerations thereof, is discussed. Specific examples and strategies to address knowledge gaps and common problem points will be given.
Regulatory Requirements for Non-target Organism Testing - Global Challenges Roma Gywnn, Biorationale, United Kingdom As microbial-based plant protection products become more established globally it raises the matter of whether the existing recommendations for non-target testing are taking into consideration the most appropriate organisms in all regions. For example, the soil fauna may be different in a tropical country and so the choice of species to test would be different to one used in a temperate country. So, if a dossier developed in the EU is submitted to Kenya and vice versa, for example, are the non-target organism types and species used in studies the most appropriate? How can evaluators from around the globe address this and what advice is available? It also has to be taken into consideration that expertise and resources available for evaluators to assess dossiers will be variable between countries, it is important to consider this when developing common approaches to work sharing reciprocity of data which are key components of a more streamlined regulatory system for microbials.
Session 4: Current Ecological/Non-Target Test Guidelines – Outlining the Issues Aquatic Safety Studies with Microbial Pesticides – retrospective analysis and recent advancements Bilgin Karaoglan, German Environment Agency (Uba), Germany Over the last 10-15 years many problems became apparent in microbial pesticide testing with aquatic organisms. Testing issues in fish, algae, aquatic plants, and especially in prolonged Daphnia studies were an important topic of discussion at EU and international level (Series on Pesticides No. 87, 2017; OECD Series on Pesticides No. 100, 2019). Based on a retrospective analysis of existing aquatic data submitted for regulatory purposes, one frequent observation in such studies was that the high test concentrations (usually at the “Maximum Hazard Dose” of 109 colony forming units(CFU)/L) may cause several problems such as high turbidity which can negatively affect biological parameters of the test organisms. This is especially notable in Daphnia studies. As daphnids are nonselective filter-feeders they may ingest large amounts of spores or suspended particles that have size ranges similar to algae. These physical effects in connection with turbidity are often mentioned as likely cause of adverse effects which complicate study interpretations, especially if proper controls (e.g. attenuated controls, sterile filtrates) are lacking. In order to overcome these problems and to develop methods better adapted to microbial pesticides, experimental Daphnia magna reproduction studies with a Bt aizawai strain were conducted in UBA-laboratories using a modified test method on the basis of OECD TG no. 211. Following a series of pretests that focused on production of stable suspensions, visual observations and cfu counting methods, the following adaptations in OECD TG 211 were considered in the definitive test: use of attenuated controls, sterile filtrate controls and increased food (algae) levels. Different filter sizes were also examined to obtain test item groups capable of removing larger particles, but without affecting microbial densities or CFUs in the test media. The basic assumption was that increased food levels (in connection with filtered test items) could compensate the above-mentioned detrimental effects frequently observed in prolonged Daphnia studies. With these findings, further proposals can be derived for improving test methods for aquatic invertebrates in conjunction with already existing knowledge from regulatory aquatic safety studies. The results of an adapted Daphnia reproduction test for microbial pesticides are presented and discussed in connection with a retrospective analysis of regulatory aquatic safety studies.
Testing Microbial Pesticides in Bees - Challenges and Current Advancements Abdulrahim Alkassab, Julius Kühn Institute, Germany Several microbial plants protection products (PPPs) have been developed as alternative to chemical PPPs, since growing concerns regarding the adverse effects of chemical PPPs on environment and non-target organism have
been reported. In contrast to chemical PPPs, they present special challenges in non-target organism testing, including bees, and risk assessment depending on their modes of action include infectivity and pathogenicity rather than toxicity alone. As the current testing guidelines are designed for testing of chemical pesticides, i.e. toxicity, they are not necessarily applicable to microbial pesticides without some modifications. Therefore, I will discuss in my presentation several issues regarding the possible modifications of the current test guidelines. For instance, how the test duration or additional pollen feeding will affect the test results to detect the possible infectivity and pathogenicity. Otherwise and due to the differences in colony and nest temperatures of different bee species as well as the different growth temperatures of the applied bacteria and fungi, some research results of our lab will be interpreted on the effect of testing conditions, i.e. temperatures, on the effects of some microbial pesticides on different bee species. Finally, some possible approach will be shown regarding the estimation of the exposure level and duration.
Issues with Non-target Insect Testing with Microbial Pesticides - CRO perspective Mark Whittaker, APIS, United Kingdom The current regulatory approach to ecotoxicology testing for microbial pesticides is identical in almost every respect to the approach developed for agrochemicals. It takes no account of the respective biology of either the microorganism or the test species, nor of the ecological relationships that have developed between them over evolutionary time. As a consequence, much of the standard ecotoxicology testing mandated for this class of plant protection product is entirely redundant from the perspective of meaningful risk assessment. This presentation will look at the extent to which the current regulatory approach to non-target arthropod testing for microbial pesticides can be considered truly scientific, and will propose some suggestions by which any genuine environmental risk posed by these products can be better evaluated.
Issues with Aquatic Organism Testing with Microbial Pesticides - CRO perspective Henry Krueger, Eurofins, United States Contract Research Organizations (CROs) have extensive experience performing GLP aquatic toxicity tests with conventional chemicals, and to a lesser extent with microbial pesticides. Through experience with conventional chemicals, CROs have developed a keen understanding of how to conduct aquatic toxicity tests with conventional chemicals and maintain test concentrations for the duration of the test. Microbial pesticides have additional inherent challenges associated with conducting aquatic studies, specifically around delivery and maintenance of the test article in an aquatic system. For conventional chemicals, test concentrations are confirmed using analytical chemistry to quantify mean measured concentrations and guidelines have been published for setting and maintaining test concentrations. The physical/chemical properties and routes of exposure of conventional chemicals are key elements in successfully running a test and setting test concentrations. Microbial pesticides will need similar guidance but face unique challenges; you are no longer testing soluble chemicals in water, but dynamic living cells that act like particles in solutions. Concepts of solubility, stability and routes of exposure require new ways of thinking. Quantification and confirmation of the test item is more complex often requiring plating that yield results reported in number of colony forming units rather than mg product/L. In aquatic testing of conventional chemicals, the limit of solubility is often used to determine the highest test concentration. For many microbial materials, solubility does not necessarily apply and the test material may actually grow and increase over the course of the test. Other issues with microbial products include limitations of carriers to aid in getting a product into solution, poor visibility in the test system, and low dissolved oxygen levels. Solvents are often used in aquatic testing to get materials into solution; however, such solvents can be highly toxic to microbial materials limiting their use. Reduced visibility can result when the product or carrier form cloudy water conditions making observations difficult during the test. Aeration may be required throughout the test to maintain oxygen levels in water due to increased oxygen demands of microbial products. Routes of exposure are also important considerations with microbial products (e.g. seed coating product vs. foliar applied product). As was done with conventional materials there is a need to work collaboratively among academia, government, and industry to develop better guidance for testing.
Aquatic Testing with Non-target Organisms and Microbial Pesticides - Challenges and Potential Solutions Maria Herrero, Valent, United States Abstract pending.
Adventures in Ecological Testing of Microbial-Based Agricultural Products Lisa Ortego, Bayer CropScience, United States The interest in and use of biological materials in crop production is increasing globally at a rapid pace. Part of the interest is that these technologies are viewed as safer alternatives to conventional chemicals. While establishing the safety of these materials is as important as for conventional chemicals, there are important distinctions between them. For example, micro-organisms need to be evaluated for their pathogenic potential which generally means longer exposure or observation periods, additional control groups, and where dose confirmation is required, quantifying exposure using plate counting methods to enumerate colony forming units. And there is an additional challenge of the test material being a particle that does not dissolve in aqueous media like dilution water for aquatic animal testing or sucrose diet used for bee testing. Over the last several years we have explored some of these testing challenges and would like to share our experiences regarding chronic honey bee testing and bumble bee testing, larval bee testing and chronic Daphnia magna testing. Some specific issues to be discussed include: High test concentrations as recommended often appear unpalatable to bees and cause aqueous exposure issues for Daphnia magna. Laboratory test duration of 30 days is difficult to achieve regarding honey bee survival and average lifespan. For bees, the particulate nature of the test material can result in: o clogging of the feeding tube restricting food access, and o difficulties in maintaining homogeneity of test material in sugar solutions. Larval honey bee testing methods, such as OECD Guidance Document No. 239, may be unreliable for certain biopesticides because the larval bee diet (and royal jelly) inhibited growth of some of the bacteria and fungi. Bumble bee husbandry differs between species and certain regional species (e.g., Bombus impatiens) may be an optimal surrogate to achieve consistency in data generation. Aquatic testing may require some “out of the box” thinking regarding test system exposure for Daphnia magna. Dose confirmation of test solutions in aquatic assays relies on growing samples on agar-based plates which has varying reliability and specificity (test solutions are not sterile). Heat attenuation used for non-viable controls may introduce physical or chemical changes absent in the test samples and complicate interpretation. Some options to consider regarding bee testing include addition of pollen to the bee diet during the test, directly dosing the bees using a pollen-based diet or feeding the bees a pre-determined quantity of treated liquid sucrose diet for a limited number of days and then supplementing with clean sucrose and pollen diet. In the aquatic area alternative exposure setups for Daphnia magna, options for creating non-viable control samples, and PCR technology for dose-confirmation are some alternatives worth considering. We will share our experiences with some of these options, but additional research is needed to determine which options may be feasible and provide the best improvements.
DAY 3 Session 5: Current Ecological/Non-Target Test Guidelines – Addressing the Issues
Challenges in Testing with Microbes in Insects - Considerations for Test Improvements Johannes Jehle, Julius Kühn Institute, Germany Microorganisms used in pest control have specific qualities as biological entities, which make them different from conventional chemical pesticides. Some microorganisms produce toxins as active principles, others are pathogens which would need to start an infection of the target pest organism; others function through competition or antibiosis. In addition, microorganisms used as biocontrol agents may have different roles in the concept of integrated pest management, as some are used in a preventive manner to avoid development of pests and diseases, whereas others are applied in a curative sense to control an existing pest population. The intrinsic characteristics of microorganisms as well as their use patterns need to be considered when both their efficacy and safety is evaluated. Since microorganisms can be highly diverse in their biological function, numerous test guidelines do not fully adequately comply with their nature. These challenges will be discussed on examples related to different test guidelines to overcome current limitations.
Working with Invertebrate Pathogens in the Laboratory - Considerations for Improving Non-target Organism Testing Caroline Hauxwell, Queensland University of Technology, Australia Registration of microbial control agents in Australia must face some of the most rigorous risk assessment regimes in the world. Requirements include not only safety and efficacy data but must satisfying strict legislation on import of non-native organisms. Laboratory bioassays attempt to address these requirements but face challenges in determining the potential harm from and exposure to these biological agents that would be found in field condition. This paper will present examples from the registration and release of microbial control agents, and discuss limits and potential improvement of laboratory risk assessment.
EU Guidance on the Assessment of Microbial Metabolites; Considerations for Non-target Testing Anne Steenbergh, Board for the Authorization of Plant Protection Products and Biocides (Ctgb), The Netherlands In addition to infectivity and pathogenicity, the potential hazards related to the use of microbial pesticides include toxicity of metabolites. The EU guidance on the risk assessment of metabolites produced by microorganisms used as plant protection active substances (SANCO/2020/12258) describes a stepwise approach for hazard identification and subsequent risk assessment of microbial metabolites. Microbial metabolites are substances which are produced by the metabolism of microorganisms. They can be broadly grouped into primary metabolites (part of normal growth and reproduction; not the focus of the risk assessment of metabolites) and secondary metabolites. Secondary metabolites are not involved in normal growth of the microorganism, but increase the fitness of the microorganism in another way. As they are not produced as part of normal growth, the conditions in which a secondary metabolite is produced depend on the function of the metabolite. These functions may include communication, nutrient sequestration and also toxicity. In the context of the use of microbial pesticides, non-target organisms may be exposed to microbial metabolites due to their presence in the product or due to in situ production upon application. As a result, the quantitative
toxicity assessment which is used for chemical active substances is in principle not appropriate for microbial active substances. This presentation will focus on how experimental data is used according to the EU guidance on metabolites. The need and constraints of non-target testing will be discussed.
Environmental Risk Assessment of Entomopathogenic fungi - Considerations for Non-target Organism Testing Lara Reinbacher, Agroscope, Switzerland The value of a plant protection product, chemical or biological, depends on its effectiveness against a target species, as well as its safety for the environment. Risk assessment schemes have therefore been developed to facilitate classification and regulation. These guidelines however are directed towards chemical substances and are in many cases not suitable for the specific requirements of biocontrol organisms. We aimed to developed a protocol for non-target testing of soil applied entomopathogenic fungi with the predatory mite Gaeolaelaps (Hypoaspis) aculeifer. G.aculeifer is frequently found in arable and grassland worldwide and is, due to its habitat in soil, at a high risk of exposure. The protocol assesses lethal and sublethal effects of the entomopathogen and considers fungal biology in terms of duration, end points and quality control. The presentation also addresses risk assessments as a limiting factor in applied research.
Conference on I nnovating M icrobial P e s t i c i d e Te s t i n g
http://oe.cd/innovating-microbial-pesticide-testing
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